1. Field of the Invention
The present invention relates to a flow regulating valve for regulating the flow rate of a fluid flowing through a flow passage.
2. Description of the Related Art
Flow regulating valves for regulating flow rates of fluids flowing flow passages are known.
Conventionally, a typical known flow regulating valve has a basic structure which is composed of a casing in which a flow passage is formed therein, a valve element which is installed in the casing and enables to change a cross-sectional area of an aperture of the flow passage, and a valve element regulating means which regulates moving amount of the valve element by using a screw mechanism, for example.
In the case of regulation of the flow rate of a fluid by a flow regulating valve, the regulation is performed by moving the valve element to approach or separate from a valve seat using a valve element regulator so as to set the cross-sectional area of the aperture of the flow passage to an appropriate value.
However, in this valve, since the flow passage formed in the casing has a sigmoid portion which is formed by a casing body and a cover, and the valve seat and valve element which face each other are installed in the flow passage as described above, the flow passage is winding and stagnation of the fluid is likely occur. Furthermore, since the flow passage is composed of a plurality of members, it is difficult to remove the fluid which has entered into gaps between these members. As a result, there is a problem in that the flow passage is difficult to clean.
For example, in a plant in which this valve is installed, in the cases of changing the kind of the fluid or performing periodic maintenance, the flow passage must be cleaned; however, this cleaning is very difficult and requires a lot of time if the valve as described above is installed in the flow passage.
Therefore, the flow passage which is made of a single member and does not have irregularities is needed in order to promote efficiency in the cleaning.
A flow regulating valve according to the present invention comprises a casing; a tube which has elasticity and both ends thereof are opened to the exterior, and is inserted and installed in the casing; and a pushing member which changes an area of an aperture of the tube.
According to this flow regulating valve, a flow passage which is made of a single member and does not have irregularities can be assured since the flow passage is formed by the tube. As a result, the flow passage in which stagnation of the fluid does not occur and cleaning thereof can easily be performed is assured, and therefore, efficiency in the cleaning can be promoted.